Ante-Nicene Fathers, Vol IX:
Epistle to Gregory and Origen's Commentary on the Gospel of John.: Chapter I

That people which was called of old the people of God was divided into twelve tribes, and over and above the other tribes it had the levitical order, which itself again carried on the service of God in various priestly and levitical suborders. In the same manner, it appears to me that the whole people of Christ, when we regard it in the aspect of the hidden man of the heart, 4455
that people which is called “Jew inwardly,” and is circumcised in the spirit, has in a more mystic way the characteristics of the tribes. This may be more plainly gathered from John in his Apocalyse, though the other prophets also do not by any means conceal the state of matters from those who have the faculty of hearing them. John speaks as follows: 4456
“And I saw another angel ascending from the sunrising, having the seal of the living God, and he cried with a loud voice to the four angels to whom it was given to hurt the earth and the sea, saying, Hurt not either the earth, or the sea, or the trees, till we have sealed the servants of our God on their foreheads. And I heard the number of them that were sealed, a hundred and forty-four thousand who were sealed, out of every tribe of the children of Israel; of the tribe of Juda were sealed twelve thousand, of the tribe of Roubem twelve thousand.” And he mentioned each of the tribes singly, with the exception of Dan. Then, some way further on, 4457
he continues: “And I saw, and behold the Lamb standing on Mount Zion, and with Him a hundred and forty-four thousand, having His name and the name of His Father written on their foreheads. And I heard a voice from heaven as the voice of many waters, and as the voice of a great thunder. And the voice which I heard was as the voice of harpers harping with their harps; and they sing a new song before the throne and before the four beasts and the elders, and no one could learn the song but the hundred and forty-four thousand who had been purchased from the earth. These are they which were not defiled with women, for they are virgins. These are they who follow the Lamb whithersover He goeth. These were purchased from among men, a first fruits to God and to the Lamb; and in their mouth was found no lie, for they are without blemish.” Now this is said in John with reference to those who have believed in Christ, for they also, even if their bodily descent cannot be traced to the seed of the Patriarchs, are yet gathered out of the tribes. That this is so we may conclude from what is further said about them: “Hurt not,” he says, “the earth, nor the sea, nor the trees, till we have sealed the servants of our God on their foreheads. And I heard the number of them that were sealed, a hundred and forty-four thousand, sealed from every tribe of the children of Israel.”